Semiconductor device

ABSTRACT

In a package of an LOC (Lead On Chip) structure in which inner lead portions are partially arranged over a major face of a semiconductor chip, there is disclosed a technique for thinning the package and speeding up signal transmission. 
     Specifically, by partially reducing the thicknesses of the signal inner leads arranged over the major face of the semiconductor chip, the thickness of a sealing resin is reduced while ensuring the mechanical strength of the package. 
     Moreover, the signal inner leads arranged over the major face of the semiconductor chip are arranged at predetermined spacings from the major face of the semiconductor chip. The power supplying inner leads are bonded to the major face of the semiconductor chip, thus providing a package having a reduced parasitic capacitance.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/563,756, filed on May 1, 2000; which is a continuation of application Ser. No. 09/139,563, filed on Aug. 25, 1999 (now U.S. Pat. No. 6,153,922).

BACKGROUND OF THE INVENTION

The present invention relates to a resin-sealed type semiconductor device having an LOC (Lead On Chip) structure and, more particularly, to a technique which is effective when applied to a thin, small-sized semiconductor package having a TSOP (Thin Small Outline Package) structure or the like.

A typical resin-sealed type semiconductor device having, an LOC structure comprises, as shown in FIG. 22 (see Japanese Patent Laid-Open No. 2-246125/1990), for example, a semiconductor chip 1 including a circuit and a plurality of external terminals formed over a major face of a semiconductor substrate; a plurality of leads, each including an inner lead portion 3A comprising inner leads 3A₁ forming signal inner leads (a first region) and a common inner lead 3A₂ for supplying a power voltage and a reference voltage (a second region: hereinafter referred to as the bus-bar leads or fixed potential leads), and an outer lean portion 3B formed integrally with the inner lead portions 3A; bonding wires 5 for electrically connecting the external terminals (pads) and the signal inner leads 3A₁ and the bus-bar leads 3A₂ of the inner lead portions 3A, respectively; and a sealer 2A for sealing the semiconductor chip 1, the inner lead portions 3A and the bonding wires 5. The signal inner leads 3A₁ and the bus-bar leads 3A₂ are arranged over the major face of the semiconductor chip 1, being separated therefrom by an insulating film 4, and the bus-bar leads 3A₂ are arranged substantially in parallel with the major face of the semiconductor chip 1.

SUMMARY OF THE INVENTION

First, a description will be presented of the items which have not: been disclosed in the publicly-known document (Japanese Patent Laid-Open No. 2-246125/1990) and have been investigated by the present inventor.

When a resin-sealed type semiconductor device having an LOC structure, as shown in FIG. 22, is applied as it is to a thin small-sized semiconductor package (TSOP), as shown in FIGS. 23 and 24(a), the entire package becomes thin (e.g., 1.0 mm), so that the resin over the inner leads 3A₁ accordingly becomes as thin as 0.195 mm. This makes it necessary to set the loop heights of the wires 5 at small values. However, in doing this, the bonding wires 5 and the bus-bar leads 3A₂ of the signal wires may contact, causing a short circuit, and this problem makes it difficult to reduce the thickness of the resin. When the wire loop heights must be suppressed to low levels, a contrivance in which an insulating coating material 20 is applied to the bus-bar leads 3A₂ is needed.

Reference will be made to the schematic construction of FIG. 23 (a top plan view of a resin-sealed type semiconductor device having a TSOP structure) and to the examples of FIG. 24(a) to FIG. 24(c) (a section of the device of FIG. 23). In this resin-sealed type semiconductor device having a TSOP structure, to a face of a semiconductor substrate of a asemiconductor chip 1 (hereinafter referred to as the “major face of the semiconductor chip 1”), where a circuit and a plurality of external terminals are formed, inner lead portions 3A, which include a plurality of signal line inner leads 3A₁ and the bus-bar leads 3A₂, which have an insulating coating material 20 applied to their upper faces, are fixed through the insulating film 4. The inner lead portions 3A and the outer lead portions 3B are formed integrally to constitute leads 3.

As shown in FIG. 23 and FIGS. 24(a) to 24(c), the signal line inner leads 3A₁ and the bus-bar leads 3A₂, which have the insulating coating material 20 applied to their upper faces, of the inner lead portions 3A, are arranged over the major face of the semiconductor chip 1 and are spaced therefrom by the insulating film 4, and the bus-bar leads 3A₂ are arranged substantially in parallel with the major face of the semiconductor chip 1.

The plurality of signal inner leads 3A₁, the bus-bar leads 3A₂ and the semiconductor chip 1 are electrically connected through the bonding wires 5 and are sealed with a mold resin (the sealing body) 2A. The thin type package 2 thus sealed is shaped by cutting the suspension leads (chip supporting leads) 3C and the outer lead portions 3B from the lead frame.

In a thin small-sized semiconductor package with a TSOP structure), which has been investigated by the present inventor, the mold resin 2A over the semiconductor chip 1 is thin, as shown in FIG. 24(a), so that problems arise, such as an appearance defect in which the bonding wires 5,such as Au wires,are seen through the upper face of the package, and a problem of exposure of the wire themselves to the outside if this thickness is made even smaller (to about 0.5 mm), as shown in FIG. 24(b), the appearance defect and the wire exposure problem become more critical.

Another problem is that when the mold resin (the sealing body) 2A over the major face of the semiconductor chip is thin, cracks are likely to occur, thereby deteriorating the reliability.

In order to lower the wire loops, as shown in FIG. 24(c), it is conceivable to eliminate the insulating tape 4 and to fix the signal inner leads 3A, and the bus-bar leads 3A₂ to the major face of the semiconductor chip 1 directly with an adhesive. If the distances (spacings) between the major face of the semiconductor chip 1 and the signal inner leads 3A₁ become short, however, the parasitic capacitance between the major face of the semiconductor chip 1 and the signal inner leads 3A₁ increases to create a problem wherein the electric characteristics may become deteriorated.

An object of the invention is to provide a technique which is capable of thinning the semiconductor package without causing deterioration of the electric characteristics thereof.

Another object of the invention is to provide a technique which is capable of suppressing the parasitic capacitance between the major face of the semiconductor chip and the leads even if the semiconductor package is thinned.

Another object of the invention is to provide a technique which is capable of ensuring a proper thickness of the sealer over the semiconductor chip of the semiconductor package even if the overall thickness of the semiconductor package is reduced.

Another object of the invention is to provide a technique which is capable of balancing the quantities of the upper and lower sealers of the semiconductor chip even if the overall thickness of the semiconductor package is reduced.

The foregoing and other objects and novel features of the invention will become apparent from the following description to be made with reference to the accompanying drawings.

Of the features to be disclosed herein. representative ones will be briefly summarized in the following.

(1) A semiconductor device has a semiconductor chip including a circuit and a plurality of external terminals formed over a major face of a semiconductor substrate, a plurality of leads each including an inner lead portion and an outer lead portion formed integrally with the inner lead portion, bonding wires electrically connecting the external terminals and the inner lead portions, respectively, and a sealing body for sealing the semiconductor chip, the inner lead portions and the bonding wires, wherein the inner lead portions are arranged over the major face of the semiconductor chip at predetermined spacings between the major face and the inner leads, and the portions of the inner leads arranged over the major face are thinner than the other portions of the inner leads.

(2) In a resin-sealed type semiconductor device-according to the aforementioned paragraph (1), the portions, arranged over the major face of the semiconductor chip, of the inner lead portions are fixed at their leading end portions to the major face of the semiconductor chip through an insulating film.

(3) In a resin-sealed type semiconductor device-according to the aforementioned paragraph (1), the portions arranged over the major face of the semiconductor chip, of the inner lead portions are fixed at their leading end portions to the major face of the semiconductor chip directly with an adhesive.

(4) A semiconductor device has a semiconductor chip including a circuit and a plurality of external terminals formed over a major face of a semiconductor substrate, a plurality of leads each including an inner lead portion having a first region, and an inner lead portion having a second region and an outer lead portion formed integrally with the inner lead portions, bonding wires electrically connecting the external terminals and the first regions and the second regions of the inner lead portions, respectively, and a sealing body for sealing the semiconductor chip, the inner lead portions and the bonding wires, wherein the first regions and the second regions of the inner lead portions are arranged over the major face of the semiconductor chip, wherein the first regions of the inner lead portions are arranged at predetermined spacings between the major face and the inner leads, wherein the portions of the inner leads arranged over the major face are thinner than the other portions of the inner leads, and wherein the inner leads arranged over the major face are fixed at their leading end portions to the major face of the semiconductor chip through an insulating film.

(5) In a resin-sealed type semiconductor device according to the aforementioned paragraph (4), the semiconductor chip is rectangular, the second regions of the inner lead portions have portions arranged substantially in parallel with the long sides of the semiconductor chip, and the parallel-arranged portions are arranged between the external terminals and the leading end portions of the inner leads.

(6) A semiconductor device has a semiconductor chip including a circuit and a plurality of external terminals formed over a major face of a semiconductor substrate, a plurality of leads each including an inner lead portion having a first region, and an inner lead portion having a second region and an outer lead portion formed integrally with the inner lead portions, bonding wires electrically connecting the external terminals and the first regions and the second regions of the inner lead portions, respectively, and a sealing body for sealing the semiconductor chip, the inner lead portions and the bonding wires, wherein the first regions and the second regions of the inner lead portions are arranged over the major face of the semiconductor chip, wherein the first regions of the inner lead portions are arranged at predetermined spacings between the major face and the inner leads, and wherein the portions of the inner leads arranged over the major face are thinner than the other portions of the inner leads and are not fixed at their leading end portions to the major face of the semiconductor chip.

(7) In a resin-sealed type semiconductor device according to the aforementioned paragraphs (4) or (6), the first regions of the inner lead portions are signal leads, whereas the second regions are fixed potential leads.

(8) A semiconductor device has a semiconductor chip including an integrated circuit and a plurality of external terminals formed over a major face of the semiconductor chip, a plurality of leads each including an inner lead portion and an outer lead portion formed integrally with the inner lead portion, portions of the inner lead portions being arranged over the major face of the semiconductor chip and being electrically connected to the corresponding external terminals, and a resin member for sealing the inner lead portions of the plurality of leads and the semiconductor chip, wherein the inner lead portions each include a first surface on the major face side of the semiconductor chip, a second surface on the opposite side to the first surface, a first portion positioned over the major face of the semiconductor chip, and a second portion formed integrally with the first portion and positioned outside the major face of the semiconductor chip, wherein the first portions of the inner lead portions are made thinner than the second portions in the thickness direction of the semiconductor chip, and wherein the first surfaces of the first portions of the inner lead portions are more spaced farther from the semiconductor chip in the thickness direction of the semiconductor chip than the first surfaces of the second portions of the inner lead portions.

(9) In a resin-sealed type semiconductor device according to the aforementioned paragraph (8), the first portions of the inner lead portions are bonded to the major face of the semiconductor chip through an insulating film.

(10) In a resin-sealed type semiconductor device according to the aforementioned paragraph (8), the first portions of the inner lead portions are bonded to the major face of the semiconductor chip through an adhesive.

(11) In a resin-sealed type semiconductor device according to the aforementioned paragraph (8), the inner lead portions and the corresponding external terminals are connected through wires.

(12) In a resin-sealed type semiconductor device according to the aforementioned paragraph (11), the plurality of leads include signal leads and fixed potential leads, the inner lead portions of the fixed potential leads are partially arranged over the major face of the semiconductor chip between the plurality of external terminals of the leading ends of the inner lead portions of the signal leads, and the wires electrically connecting the inner lead portions of the signal leads and the corresponding external terminals are so arranged as to cross over portions of the inner lead portions of the fixed potential leads.

(13) A semiconductor device has a semiconductor chip including an integrated circuit and a plurality of external terminals formed over a major face of the semiconductor chip, a plurality of signal leads each including an inner lead portion and an outer lead portion formed integrally with the inner lead portion, portions of the inner lead portions being arranged over the major face of the semiconductor chip and being electrically connected to the corresponding external terminals through wires, fixed potential leads each including an inner lead portion and an outer lead portion formed integrally with the inner lead portions, the inner lead portions being partially arranged over the major face of the semiconductor chip and being electrically connected to the corresponding external terminals, and a resin member for sealing the inner lead portions of the plurality of signal leads, the inner lead portions of the fixed potential leads, and the semiconductor chip, wherein the inner lead portions of the signal leads each include a first surface on the major face side of the semiconductor chip, a second surface on the opposite side to the first surface, a first portion positioned over the major face of the semiconductor chip, and a second portion formed integrally with the first portions and positioned outside the major face of the semiconductor chip, wherein the first portions of the inner lead portions of the signal leads are made thinner than the second portions in the thickness direction of the semiconductor chip, wherein the first surfaces of the first portions of the inner lead portions the signal leads are spaced farther from the semiconductor chip in the thickness direction of the semiconductor chip than the first surfaces of the second portions of the inner lead portions, wherein the inner lead portions of the fixed potential leads are partially arranged over the major face of the semiconductor chip between the leading ends of the inner lead portions of the signal leads and the plurality of external terminals, and wherein the inner lead portions of the fixed potential leads are partially arranged lower in the thickness direction of the semiconductor chip than the leading ends of the inner lead portions of the signal leads.

(14) In a resin-sealed type semiconductor device according to the aforementioned paragraph (13), the inner lead portions of the fixed potential leads are partially bonded to the major face of the semiconductor chip with an adhesive, and the inner lead portions of the signal leads are spaced at their leading ends from the major face of the semiconductor chip.

(15) In a resin-sealed type semiconductor device according to the aforementioned paragraph (13), the inner lead portions of the signal leads are bonded at their leading ends to the major face of the semiconductor chip through an insulating film.

(16) In a resin-sealed type semiconductor device according to the aforementioned paragraph (13), the wires electrically connecting the inner lead portions of the signal leads and the corresponding external terminals are so arranged as to cross over portions of the inner lead portions of the fixed potential leads.

(17) A semiconductor device has a semiconductor chip including an integrated circuit and a plurality of external terminals formed over a major face of the semiconductor chip, a plurality of signal leads each including an inner lead portion and an outer lead portion formed integrally with the inner lead portions, portions of the inner lead portions being arranged over the major face of the semiconductor chip and being electrically connected to the corresponding external terminals through wires,fixed potential leads each including an inner lead portion and an outer lead portion formed integrally with the inner lead portion, the inner lead portions being partially arranged over the major face of the semiconductor chip and being electrically connected to the corresponding external terminals, and a resin member for sealing the inner lead portions of the plurality of signal leads, the inner lead portions of the fixed potential leads, and the semiconductor chip, wherein the inner lead portions of the signal leads each includes a first surface on the major face side of the semiconductor chip, a second surface on the opposite side to the first surface, a first portion positioned over the major face of the semiconductor chip, and a second portion formed integrally with the first portion and positioned outside the major face of the semiconductor chip, wherein the first portions of the inner lead portions of the signal leads are made thinner than the second portions in the thickness direction of the semiconductor chip, wherein the first portions of the inner lead portions of the signal leads have leading end portions to be connected to the wires, wherein the first surfaces of the first portions of the inner lead portions of the signal leads other than the leading end portions are spaced father from the semiconductor chip in the thickness direction of the semiconductor chip than the first surfaces of the second portions of the inner lead portions, wherein the first portions of the inner lead portions of the signal leads are arranged lower in the thickness direction of the semiconductor chip than the first portions of the inner lead portions of the signal leads other than the leading end portions, wherein the inner lead portions of the fixed potential leads are partially arranged over the major face of the semiconductor chip between the leading end portions of the first portions of the inner lead portions of the signal leads and the plurality of external terminals, and wherein the inner lead portions of the fixed potential leads are partially arranged lower in the thickness direction of the semiconductor chip than the first portions of the inner lead portions of the signal leads other than the leading end portions.

(18) In a resin-sealed type semiconductor device according to the aforementioned paragraph (17), portions of the inner lead portions of the fixed potential leads and the leading end portions of the inner lead portions of the signal leads are bonded to the major face of the semiconductor chip with an adhesive.

(19) In a resin-sealed type semiconductor device according to the aforementioned paragraph (17), the wires connecting the inner lead portions of the signal leads and the corresponding external terminals are so arranged as to cross over portions of the inner lead portions of the fixed potential leads.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device of Embodiment 1 of the invention;

FIGS. 2(a) to 2(c) are sections taken along lines A-A′, B-B′ and C-C′ in FIG. 1, respectively;

FIG. 3 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device of Embodiment 2 of the invention;

FIG. 4 is a section taken along line A-A′ of FIG. 3;

FIG. 5 is an enlarged section view of a part enclosed by a circle M in FIG. 4;

FIG. 6 is a section taken along line B-B′ of FIG. 3;

FIGS. 7(a) to 7(c) are diagrams for explaining a method of bonding wires to signal line inner leads;

FIGS. 8(a) to 8(c) are diagrams for explaining another method of bonding wires to signal line inner leads;

FIG. 9 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device of Embodiment 3 of the invention;

FIG. 10 is a section taken along line A-A′ in FIG. 9;

FIG. 11 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device of Embodiment 4 of the invention;

FIG. 12 is a section taken along line A-A′ in FIG. 11;

FIG. 13 is a schematic top plan view showing a construction of a resin-sealed type semiconductor device of Embodiment 5 of the invention;

FIG. 14 is a section taken along line A-A′ of FIG. 13;

FIG. 15 is a section taken along line B-B′ of FIG. 13;

FIG. 16 is a diagram showing a region H where the back faces of the inner lead portions are half-etched;

FIGS. 17(a) to 17(d) are diagrams showing various shapes of one of the external leads (outer leads);

FIG. 18 is a schematic top plan view showing the construction of a module of a semiconductor storage device of Embodiment 6 of the invention;

FIG. 19 is a side elevation of the module of FIG. 18;

FIGS. 20(a) and 20(b) are schematic top and bottom plan views, respectively, showing the construction of an electronic device of Embodiment 7 of the invention;

FIG. 21 is a side elevation of the device of FIGS. 20(a) and 20(b);

FIG. 22 is a partially cut-away schematic perspective view showing the entire construction of a conventional resin-sealed type semiconductor device having an LOC structure;

FIG. 23 is a schematic top plan view showing a construction of a resin-sealed type semiconductor device having a TSOP structure, which has been investigated by us; and

FIG. 24 is a section taken along line A-A′ in FIG. 23.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The invention will be described in detail in connection with various embodiments with reference to the accompanying drawings.

Throughout all the drawings for explaining the features of the invention, those portions having identical functions are designated by identical reference numerals, and their repeated description will be omitted

(Embodiment 1)

FIG. 1 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device representing Embodiment 1 of the invention; FIG. 2(a) is a section taken along line A-A′ of FIG. 1; FIG. 2(b) is a section taken along line B-B′ of FIG. 1; and FIG. 2(c) is a section taken along line C-C′ of FIG. 1.

Throughout all the embodiments of the invention, the semiconductor chip is sealed in a resin-sealed type package having a TSOP structure. The resin-sealed type package of this kind adopts an LOC (Lead On Chip) structure in which inner lead portions 3A are arranged over a rectangular semiconductor chip 1, as shown in FIG. 1.

The inner lead portions 3A are integral at their outer ends with outer lead portions 3B. Signals applied to the outer lead portions 3B conform to the standards individually and the outer lead portions 3B are correspondingly numbered. In FIG. 1, the upper lefthand end is the 1st terminal, and the lower lefthand end is the 16th terminal. The lower righthand end is the 17th terminal, and the upper righthand end is the 32th terminal. In short, the package of the present TSOP structure has 32 terminals.

The 1st, 7th and 16th terminals are for the power voltage Vcc, such as the operating voltage of 5 volts (V) or 3 volts (V) of the circuit. The 17th, 27th and 32nd terminals are for the reference voltage Vss of 0 volts (V), for example.

The inner lead portions 3A each includes, as shown in FIGS. 1 and 2(a) to 2(c), a plurality of signal line inner leads (first regions) 3A₁ and two bus-bar leads (second regions) 3A₂. The bus-bar leads are leads for feeding the power voltage and the reference voltage to the semiconductor chip and will also be referred to as the “fixed potential leads”.

The plurality of signal line inner leads 3A₁ are extended across the individual long sides of the rectangle of the semiconductor chip 1 to the center region of the semiconductor chip 1.

The signal line inner leads (the first regions) 3A₁ are arranged, as shown in FIG. 2(b), over the major face (the major face of the semiconductor substrate, over which the circuit and a plurality of external terminals are formed) of the semiconductor chip 1, at predetermined spacings S (predetermined distances) between the major face and inner leads 3A₁₂, which are made thinner than the other portions of the inner leads 3A₁.

The leading end portions 3A₁₁ of the thinned signal line inner leads (the first regions) 3A₁₂ are fixed to the major face of the semiconductor chip 1 through an insulating film 4, as shown in FIG. 1 and FIGS. 2(b) and 2(c).

The individual leading end portions 3A₁₁ of the plurality of signal line inner leads 3A₁ are individually connected through bonding wires 5 to bonding pads (the external terminals) 1A arrayed at the central portion of the semiconductor chip 1.

The two bus-bar leads 3A₂ are formed over the major face of the semiconductor chip 1, as shown in FIG. 1, each include portions 3A₂₁ arranged substantially in parallel with the long sides of the chip 1, and projections 3A₂₂ arranged substantially in parallel with the short sides of the chip 1 and having regions to which the bonding wires 5 are bonded, and are made integrally of the same material. At the portions 3A₂₁ of the bus-bar leads 3A₂, the projections 3A₂₂ are made integral with the portions 3A₂₁ at a plurality of predetermined positions. These projections 3A₂₂ are fixed with the insulating film 4. The portions 3A₂₁ are so arranged to be low by forming steps D so as to be closer to the major face of the chip 1 than the projections 3A₂₂. By means of the steps, it is possible to prevent the bus-bars and the wires 5 for the signal leads from contacting. The object of bonding the wires 5 to the projections 3A₂₂ is to make uniform the lengths, bondability and electric characteristics of the wires uniform.

The leading end portions 3A₁₁ of the signal inner leads 3A₁₂ and the bonding pads 1A of the semiconductor chip 1, and the projections 3A₂₂ formed at the parallel portions 3A₂₁ of the bus-bar leads 3A₂ and the bonding pads 1A of the semiconductor chip 1,are bonded respectively by the bonding wires 5 and are electrically connected. The semiconductor chip 1, the inner lead portions 3A and the bonding wires 5 are sealed with a mold resin (sealing body) 2A. A package 2 having this sealed TSOP structure is shaped by cutting suspension leads (chip supporting leads) 3C and the outer lead portions 3B from the lead frame. In this embodiment, the portions 3A₂₁ are close to the chip major face, but are not bonded with adhesive or the like. The insulating tape 4 has a structure in which an epoxy or polyimide adhesive is applied to both sides of a base made of a polyimide resin.

The bonding wires 5 may be gold wires. The method of forming the wires 5 may be the nail head bonding method or the ultrasonic thermocompression bonding method. These gold wires may be replaced by aluminum wires, copper wires or coated wires which are prepared by coating the surfaces of metal wires with an insulating resin.

The dimensions of the resin sealed type semiconductor device of Embodiment 1 are shown in FIG. 2(a) to FIG. 2(c) (the unit is a millimeter: mm), wherein the thickness of the resin-sealed type semiconductor device is 0.5 to 0.6 mm, the thickness of the mold resin (the sealing body) over the inner lead portions 3A on the major face of the semiconductor chip 1 is 0.06 to 0.11 mm, the thickness of the sealer 2A below the face opposed to the major face of the semiconductor chip 1 is 0.06 to 0.11 mm, and the thickness of the sealer 2A over the crests of the bonding wires 5 is 0.07 mm or more (the minimum value is 0.07 mm).

The thickness of the semiconductor chip 1 is 0.2 to 0.28 mm; the thickness of the portions 3A₂₁, arranged over the major face of the semiconductor chip 1, of the bus-bar leads 3A₂ is 0.06 to 0.07 mm; the thickness of the signal inner leads 3A₁₂ is 0.06 to 0.07 mm; the thickness of the insulating film 4 is 0.05 mm; and the thicknesses of the inner lead portions 3A and the outer lead portions 3B are individually about 0.125 mm.

Next the assembling steps for arranging the inner lead portions 3A over the major face of the semiconductor chip 1 will be described.

Assembling Steps:

{circle around (1)}: Preparing a flat frame which includes the inner lead portions 3A having the plurality of signal line inner leads 3A₁ and the two bus-bar leads 3A₂, and the outer lead portions 3B integrated with the inner lead portions 3A;

{circle around (2)}: Sticking the insulating tape 4 to the plurality of signal line inner leads 3A₁ of the inner lead portions 3A, and shaping the two bus-bar leads 3A₂ to form the steps D;

{circle around (3)}: Positioning the lead frame over the semiconductor chip 1 in such a way that the plurality of signal line inner leads 3A₁ are extended across the individual long sides of the rectangle of the semiconductor chip 1 and to the center side of the semiconductor chip 1 (see FIGS. 1 and 2); and

{circle around (4)}: After this positioning, performing a heat treatment (at 400° C. for 1 sec.) so as to bond the major face of the semiconductor chip 1 and the lead frame through the insulating tape.

A description will be provided later of the method of making the inner leads 3A₁₂ thinner than the other portions of the inner leads 3A₁. The steps of the leads may be formed before the tape is stuck. The insulating tape 4 is given a structure in which a thermoplastic polyimide adhesive having a thickness of 0.015 mm is applied to both sides of a thermoplastic polyimide tape having a thickness of 0.03 mm, the adhesive having a thickness of about 0.05 mm as a whole.

In the resin-sealed type semiconductor having the TSOP structure shown in FIG. 24(a), the thickness of the resin-sealed type semiconductor device is 1.0 mm; the thickness of the mold resin (the sealing body) over the inner lead portion 3A is 0.06 to 0.11 mm; the thickness of the mold resin (the sealing body) below the face, opposed to the major face, of the semiconductor chip 1 is 0.32 mm; the thickness of the mold resin (the sealing body) 2A over the crests of the bonding wires 5 is 0.07 mm or more (the minimum value is 0.07 mm); the thickness of the semiconductor chip 1 is 0.28 mm; the thickness of the bus-bar leads 3A₂ is 0.125 mm; the individual thicknesses of the signal inner leads 3A₁ and the outer leads 3B are 0.125 mm; and the thickness of the insulating film 4 is 0.08 mm.

In Embodiment 1, as seen from FIGS. 2(a) to 2(c) and 24(a), over the major face of the semiconductor chip 1, predetermined spacings S are provided between the major face and the inner leads 3A₁₂ which are made thinner than the other portions of the inner leads 3A₁. As a result, the semiconductor package 2 can be made thin without causing short-circuit between the bonding wires 5 of the signal lines and the bus-bar leads 3A₂, even if an insulating coating material 20 is not applied to the bus-bar leads 3A₂₁. Since the upper faces of the inner leads 3A₁₁ to which the wires are connected can be lowered, moreover, the heights of the wire loops can be lowered to reduce the thickness of the package. The thickness of the outer leads is made greater than that of the inner leads 3A₁₂ in such a way as to provide a sufficient mechanical strength, strong enough to prevent deformation of the leads, as might otherwise be caused by an undesired external force applied from the outside of the package, and to support the weight of the package, when the package is surface-mounted. Consequently, the reliability of the package can be improved.

Even if the semiconductor package 2 is made thin, moreover, the parasitic capacitance can be reduced to speed up the operation of the resin-sealed type semiconductor device by providing predetermined spacings S through the insulating film 4 (the thickness is 0.05 mm) between the major face of the semiconductor chip 1 and the inner lead portions 3A.

Even if the semiconductor package 2 is made thin, moreover, it is possible to ensure a proper thickness (about 0.06 to 0.11 mm) of the sealer over the major face of the semiconductor chip 1 of the semiconductor package 2.

By making the inner leads 3A₁₂ thinner than the other portions of the inner leads 3A₁, moreover, the sealers over and under the semiconductor chip 1 can be balanced in quantity by bringing the projections of the outer lead portions 3B closer to the central portion in the thickness direction of the semiconductor package 2, even though the thickness of this semiconductor package 2 has been reduced. This makes it possible to prevent the semiconductor package 2 from being warped because of thermal expansion. At this time, it is preferable that the lower faces of the inner leads 3A₁, not arranged over the chip 1, be positioned below the major face of the semiconductor chip 1

In Embodiment 1, moreover, in place of the insulating film 4, adhesive may be employed to bond the leading end portions 3A₁₁ of the inner leads to the major face of the chip. Though the parasitic capacitance between the chip and the leads increases, the leading end portions 3A₁₁ can be lower by the thickness of the base of the insulating film 4, so that the wire loops can be lowered. As a result, it is possible to reduce the thickness the package as a whole. This package is suited especially for devices, such as flash memories, whose operating speeds do not need to be relatively high.

(Embodiment 2)

FIG. 3 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device representing an Embodiment 2 of the invention; FIG. 4 is a section taken along line A-A′ of FIG. 3; FIG. 5 is an enlarged view of a part enclosed by a circle M in FIG. 4; and FIG. 6 is a section taken along line B-B′ of FIG. 3.

In a resin-sealed type semiconductor device representing Embodiment 2, as shown in FIGS. 3 to 6, the portions 3A₂₁, arranged substantially in parallel with the long sides of the semiconductor chip 1, of the bus-bar leads 3A₂, are fixed directly with adhesive 6. The plurality of signal line inner leads 3A₁ are lifted at their leading ends 3A₁₁ from the chip major face, and no insulating film is interposed to provide spacings (distance of 0.05 mm) S between the major face of the semiconductor chip 1 and the thinned portions 3A₁₂ of the plurality of signal line inner leads 3A₁. The adhesive 6 employed is, e.g., a thermoplastic polyimide adhesive. This adhesive 6 has a thickness of about 0.01 mm after being applied.

As shown in FIG. 4, the plurality of signal inner leads 3A₁ are electrically connected to the semiconductor chip 1 by bonding the bonding wires (gold wires) 5 directly to the bonding pads 1A on the major face of the semiconductor chip 1. Specifically, the semiconductor chip 1 and the signal line inner leads 3A₁ are electrically connected by pressing the lifted thin portions A₁₂ of the signal line inner leads 3A₁ to the major face of the semiconductor chip 1 by a lead frame presser to bond the bonding wires 5 to the leading end portions 3A₁₁ and by bonding the other ends of the bonding wires 5 to the bonding pads 1A on the major face of the semiconductor chip 1.

Likewise, as shown in FIG. 6, the protrusions 3A₂₂ and the joints 3A₂₁′ of the bus-bar leads 3A₂ and the bonding pads 1A on the major face of the semiconductor chip 1 are individually bonded by the bonding wires 5 to connect the semiconductor chip 1 and the bus-bar leads 3A₂ electrically. After this, they are sealed with the sealer (resin) 2A.

The bonding pads 1A on the major face of the semiconductor chip 1 have a structure, as seen in FIG. 5, in which an insulating oxide film 1B₂ is formed on an inner electrode 1B₁ on an Si substrate 1B and in which there are sequentially formed thereover a first tungsten (W) alloy 1B₃, a second tungsten (W) alloy 1B₄, an aluminum (Al) alloy 1B₅, a first titanium (Ti) alloy 1B₆, a second titanium (Ti) alloy 1B₇, a first insulating oxide film 1B₈, a second insulating film 1B₉ and a resin PiQ 1B₁₀. Moreover, a hole is formed to expose the face of the aluminum (Al) alloy 1B₅ to the outside.

Even if the inner lead portions 3A are fixed to the major face of the semiconductor chip 1 directly with the adhesive 6, the insulating polyimide resin (PiQ) is formed at the uppermost layer of the major face of the semiconductor chip 1, as shown in FIG. 5, so that the insulation of the portions other than the inner lead portions 3A and the bonding pads 1A of the semiconductor chip 1 can be ensured.

The assembling steps for arranging the inner lead portions 3A over the major face of the semiconductor chip 1 of the resin-sealed type semiconductor device of Embodiment 2 will be described.

Assembling Steps:

{circle around (1)}: Preparing a flat frame having a plurality of leads 3;

{circle around (2)}: Applying adhesive 6 to the two bus-bar leads 3A₂, and shaping the lead frame to form the steps D (Here, the adhesive 6 may be applied after the step formation);

{circle around (3)}: over the semiconductor chip 1, positioning the lead frame in such a way that the plurality of signal line inner leads 3A₁ may extend across the individual long sides of the rectangle of the semiconductor chip 1 and to the center region of the semiconductor chip 1 (see FIG. 3); and

{circle around (4)}: After this positioning, bonding the chip and the lead frame with the adhesive 6.

FIGS. 7(a) to 7(c) are diagrams for explaining a method for bonding the bonding wires 5 to the signal line inner leads. FIG. 7(a) shows the state before the wire bonding; FIG. 7(b) shows the state during the wire bonding; and FIG. 7(c) shows the state after the wire bonding. Numeral 21 designates a stage, and numeral 22 designates a lead frame presser.

In a method of bonding the bonding wires 5 by pressing the listed leading end portion 3A₁₁ of the signal line inner lead 3A₁ to the major face of the semiconductor chip 1, as shown in FIG. 7(a), the semiconductor chip 1 is disposed over the stage 21 to position the lifted leading end portion 3A₁₁ of the signal line inner lead 3A₁. Next, as shown in FIG. 7(b), after the positioning of the inner lead, the lead frame presser 22 is lowered, but the stage 21 is raised to bond the bonding wire 5 to the leading end portion 3A₁₁ while pressing the signal line inner lead 3A₁ to the major face of the semiconductor chip 1 over the stage 21. After this, as shown in FIG. 7(c), the lead frame presser 22 is raised, and the stage 21 is lowered to release the pressing force, thereby to return the leading end portion 3A₁₁ of the signal line inner lead 3A₁ to the lifted state.

FIGS. 8(a) to 8(c) are diagrams for explaining another method for bonding the bonding wire 5 to the signal line inner lead. FIG. 8(a) shows the state before the wire bonding; FIG. 8(b) shows the state during the wire bonding; and FIG. 8(c) shows the state after the wire bonding. In the method of bonding the bonding wire 5 to the signal line inner lead, as shown in FIG. 8(a), the semiconductor chip 1 is disposed over a fixed stage 21 to position the lifted leading end portion 3A₁₁ of the signal line inner lead 3A₁. Next, as shown in FIG. 8(b), after the positioning of the inner lead, the lead frame presser 22 is lowered to bond the bonding wire 5 to the leading end portion 3A₁₁ while pressing the signal line inner lead 3A₁ on the major face of the semiconductor chip 1 over the stage 21. After this, as shown in FIG. 8(c), the lead frame presser 22 is raised to release the pressing force, thereby to return the leading end portion 3A₁₁, of the signal line inner lead 3A₁ to the lifted state.

In Embodiment 2, the portions 3A₂₁, arranged substantially in parallel with the long sides of the semiconductor chip 1, of the bus-bar leads 3A₂ are fixed directly with the adhesive 6 in such a way that the plurality of signal line inner leads 3A₁ are lifted at their leading ends, no insulating film is interposed and the spacings (the distances are 0.05 mm) S are provided between the major face of the semiconductor chip 1 and the plurality of signal line inner leads 3A₁. As a result, the parasitic capacitance can be reduced to achieve effects similar to those of Embodiment 1. Moreover, the insulating film 4 (having a thickness of 0.05 mm) is not interposed between the major face of the semiconductor chip 1 and the inner lead portions 3A, so that the steps of manufacture and the cost can be accordingly reduced.

(Embodiment 3)

FIG. 9 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device representing Embodiment 3 of the invention, and FIG. 10 is a section taken along line A-A′ of FIG. 9.

In the resin-sealed type semiconductor device of Embodiment 3, as shown in FIGS. 9 and 10, the invention is applied to the case in which the portions 3A₂₁ arranged substantially in parallel with the long sides of the semiconductor chip 1, of the bus-bar leads 3A₂ of the inner lead portions 3A of Embodiment 1, are not used. The structure of the other portions is identical to that of Embodiment 1.

The assembling steps for arranging the inner lead portions 3A over the lead portions 3A over the major face of the aforementioned semiconductor chip 1 will be described.

Assembling Steps:

{circle around (1)}: Preparing a flat frame having the insulating film 4;

{circle around (2)}: Over the semiconductor chip 1, positioning the lead frame in such a way that the plurality of signal line inner leads 3A₁ may extend to the center region of the semiconductor chip 1 (see FIGS. 9 and 10); and

{circle around (3)}: After this positioning, bonding the lead frame to the major face of the semiconductor chip 1 through the insulating film 4.

With this construction, it is possible to achieve effects similar to those of Embodiment 1. Since the bus-bar leads 3A₂ are not employed, moreover, the steps of manufacture and the cost can be accordingly reduced.

(Embodiment 4)

FIG. 11 is a schematic top plan view showing the construction of a resin-sealed type semiconductor device representing Embodiment 4 of the invention, and FIG. 12 is a section taken along line A-A′ of FIG. 11.

In the resin-sealed type semiconductor device of Embodiment 4, as shown in FIGS. 11 and 12, the leading ends 3A₁₁ of the plurality of signal line inner leads 3A₁ of Embodiment 3 are fixed to the major face of the semiconductor chip 1 directly with the adhesive 6, and no insulating film 4 is interposed. The spacings (the distances are 0.05 mm) for reducing the parasitic capacitance are provided between the major face of the semiconductor chip 1 and the plurality of signal line inner leads 3A₁₂.

The assembling steps for arranging the inner lead portions 3A over the major face of the aforementioned semiconductor chip 1 of the resin-sealed type semiconductor device of Embodiment 4 will be described.

Assembling Steps:

{circle around (1)}: Preparing a frame which is configured to form a step and of which the leading ends 3A₁₁ of the inner lead portions 3A are coated with the adhesive 6.

{circle around (2)}: Over the semiconductor chip 1, positioning the lead frame in such a way that the plurality of signal line inner leads 3A₁ may extend to the center region of the semiconductor chip 1 (see FIGS. 11 and 12); and

{circle around (3)}: After this positioning, bonding the major face of the semiconductor chip 1 and the lead frame through the adhesive 6.

With this construction, it is possible to achieve effects similar to those of Embodiment 3. Since the bus-bar leads 3A₂ and the insulating film 4 are not employed, moreover, the steps of manufacture and the cost can be accordingly reduced.

(Embodiment 5)

FIG. 13 is a schematic top plan view showing a construction of a resin-sealed type semiconductor device representing Embodiment 5 of the invention; FIG. 14 is a section taken along line A-A′ of FIG. 13; and FIG. 15 is a section taken along line B-B′ of FIG. 14.

In the resin-sealed type semiconductor device of Embodiment 5, as shown in FIGS. 13 and 14, the portions 3A₂₁, arranged substantially in parallel with the major face of the semiconductor chip 1, of the bus-bar leads 3A₂, are fixed directly with the adhesive 6. The individual leading ends of the plurality of signal line inner leads 3A₁ are fixed to the major face of the semiconductor chip 1 directly with the adhesive 6, and the spacings (the distances are 0.05 mm) for ensuring the proper capacitance are provided without any insulating film between the major face of the semiconductor chip 1 and the plurality of signal line inner leads 3A₁.

The assembling steps for arranging the inner lead portions 3A over the major face of the semiconductor chip 1 of the resin-sealed type semiconductor device of Embodiment 5 will be described.

Assembling Steps:

{circle around (1)}: Preparing a flat frame and shaping the frame to form steps D;

{circle around (2)}: Applying adhesive to the portions 3A₂₁, arranged substantially in parallel with the long sides of the semiconductor chip 1, of the bus-bar leads 3A₂ the projections A₂₂, and the leading end portions 3A₁₂ of the plurality of signal line inner leads 3A₁;

{circle around (3)}: Over the semiconductor chip 1 of the lead frame, positioning the portions 3A₂₁, arranged substantially in parallel with the long sides of the semiconductor chip 1, of the bus-bar leads 3A₂ in such a way that the leading end portions 3A₁₁ of the plurality of signal line inner leads 3A₁ may extend to the center region of the semiconductor chip 1 (as shown in FIG. 15); and

{circle around (4)}: After this positioning, bonding the lead frame to the major face of the semiconductor chip 1 with the adhesive 6 (see FIGS. 14 and 15).

After this bonding, the semiconductor chip 1 and the signal line inner leads 3A₁ are electrically connected by bonding the one ends of the bonding wires 5 to the leading end portions 3A₁₁ of the inner leads 3A₁₂ and by bonding the other ends of the bonding wires 5 to the bonding pads 1A on the major face of the semiconductor chip 1. Likewise, the semiconductor chip 1 and the bus-bar leads 3A₂ are electrically connected by connecting the portions 3A₂₂ integrated with the portions 3A₂₁ arranged substantially in parallel with the long sides of the semiconductor chip 1, and the bonding pads 1A on the major face of the semiconductor chip 1 through the bonding wires 5. After this, they are sealed with the resin 2A by a transfer mold method.

With this construction, it is possible to achieve effects similar to those of Embodiment 1. Since the insulating film 4 is not used, moreover, it is possible to reduce the steps of manufacture and the cost. Since the leading end portions 3A₁₁ of the signal inner leads 3A₁ are arranged closer to the chip major face, moreover, it is possible to lower the levels of the wire loops.

In Embodiments 1 to 5, the thinned portions 3A₁₁ and 3A₁₂ of the signal line inner leads 3A₁ and the thinned portions 3A₂₁ and 3A₂₁′ of the bus-bar leads 3A₂ are formed by half-etching or coining the back faces of the inner lead portions which are provided in the area H (of a slightly larger rectangular shape than the chip) enclosed by a broken line in FIG. 16.

The external leads (outer leads) are worked into a J-bend (letter J) shape, as shown in FIG. 17(a), and are worked, if necessary, into a flat shape, as shown in FIG. 17(b), an inverted L shape, as shown in FIG. 17(c), or a Z shape, as shown in FIG. 17(d).

Here, the structure of the foregoing Embodiments having one semiconductor chip 1 of one layer have been described, but the thin resin-sealed type semiconductor device of the invention can also be applied to the case in which two or more semiconductor chips or semiconductor packages are stacked to increase the storage capacity.

(Embodiment 6)

FIG. 18 is a schematic top plan view showing a construction of a semiconductor storage module representing Embodiment 6 of the invention, and FIG. 19 is a side elevation of FIG. 18. Reference numeral 30 designates a mounting board; numeral 31 denotes a stack in which two semiconductor storage devices,such as DRAMs, are stacked; numeral 32 denotes a chip capacitor; and numeral 33 denotes the terminals of the semiconductor storage module. Any of the packages of Embodiments 1 to 5 can be applied to the individual packages constituting the stack 31.

In the semiconductor storage module of embodiment 6, as shown in FIGS. 18 and 19, eight stacks 31, in which two semiconductor storage devices,such as DRAMs, are individually stacked, are mounted on both sides of the board 3. The chip capacitors 32 are mounted on one peripheral portion of the plane of the mounting board 30, and the terminals 33 of the semiconductor storage module are mounted on one edge face of the mounting board 3. With this construction, it is possible to provide a small-sized large-capacity thin semiconductor storage module. The thicknesses of the stacks 31 are about 1.2 to 1.3 mm at the maximum.

(Embodiment 7)

FIGS. 20(a), 20(b) and 21 show the construction of an electronic device representing Embodiment 7 of the invention. FIG. 20(a) is a top plan view of one face, FIG. 20(b) is a top plan view of the other face, and FIG. 21 is a side elevation of the device. In FIGS. 20(a), 20(b) and 21, numeral 34 designates a QFP in which a microcomputer is mounted; numeral 35 denotes a QFP in which a driver IC is mounted; and numeral 36 denotes a stack in which two semiconductor storage devices, such as flash memories are stacked. Any of the packages of Embodiments 1 to 5 may be applied to the individual packages constituting the stack 36.

In the semiconductor storage module of Embodiment 7, as shown in FIGS. 20(a), 20(b) and 21, there are mounted on one face (front face) of the board 30, three stacks 36 of semiconductor storage devices,such as flash memories, a microcomputer (QFP) 34, a driver (QFP) 35 and chip capacitors 32, and there are mounted on the other face (back face) eight stacks 36 in each of which two semiconductor storage devices, such as flash memories, are stacked, and chip capacitors 32 with this construction, it is possible to provide an electronic device of a small size having a large storage capacity. As a result, it is possible to provide an electronic card capable of processing massive amounts of information with high accuracy. The thicknesses of the stacks 36 are 1.2 to 1.3 mm at the maximum, which are substantially equal to those of the QFPs 34 and 35.

Although our invention has been specifically described in conjunction with various embodiments, it should not be limited thereto,but can naturally be modified in various manners without departing from the gist thereof.

The effects of representative features of the invention disclosed herein will be briefly described in the following.

(1) In a resign-sealed type semiconductor device having bus-bar leads, the signal inner leads (the first regions of the inner lead portions) are so arranged over the major face of the semiconductor chip as to provide predetermined spacings between the major face and the inner leads, and portions of the inner leads are made thinner than those of the other portions. As a result, even if no insulating coating material is applied to the bus-bar leads, the thickness of the semiconductor package can be reduced without causing any short-circuit between the signal line bonding wires and the bus-bar leads.

(2) In a resin-sealed type semiconductor device having bus-bar leads, even if the, semiconductor package is thinned, a proper capacitance can be ensured by sandwiching the insulating film between the major face of the semiconductor chip and the inner lead portions to provide predetermined spacings. As a result, the required electric characteristics can be achieved by the proper capacitance of the resin-sealed type semiconductor device.

(3) In a resin-sealed type semiconductor device having bus-bar leads, even if the semiconductor package is thinned, it is possible to ensure a proper thickness for the sealer over the major face of the semiconductor chip of the semiconductor package.

(4) In a resin-sealed type semiconductor device having bus-bar leads, even if the semiconductor package is thinned, the upper and lower sealers of the semiconductor chip can be balanced by bringing the projections of the outer leads closer to the central portion in the direction of the thickness of the semiconductor package. As a result, it is possible to prevent warpage which might otherwise be caused by the difference in the coefficients of thermal expansion of the semiconductor package.

(5) In a resin-sealed type semiconductor device having bus-bar leads, the signal inner leads (the first regions of the inner lead portions) are so arranged over the major face of the semiconductor chip as to provide predetermined spacings between the major face and the inner leads, and only the bus-bar leads are directly fixed to the major face of the semiconductor chip with adhesive. As a result, the steps of manufacture and the cost can be reduced correspondingly to the elimination of the insulating film.

(6) In a resin-sealed type semiconductor device not having bus-bar leads, the signal inner leads are so arranged over the major face of the semiconductor chip as to provide predetermined spacings between the major face and the inner leads, and the portions of the inner leads are made thinner than those of the other portions are fixed at their leading end portions to the major face of the semiconductor chip through the insulating film. This ensures the proper insulation between the semiconductor chip and the leads.

(7) In a resin-sealed type semiconductor device not having bus-bar leads, even if the semiconductor package is thinned, a proper capacitance can be ensured by interposing the insulating film between the major face of the semiconductor chip and the inner lead portions to provide predetermined spacings. As a result, the required electric characteristics can be achieved by the proper capacitance of the resin-sealed type semiconductor device. As a result, the steps ol manufacture and the cost can be reduced correspondingly to the elimination of the insulating film.

(8) In a resin-sealed type semiconductor device not having bus-bar leads, even if the semiconductor package is thinned, it is possible to ensure a proper thickness for the sealer over the major face of the semiconductor chip of the semiconductor package.

(9) In a resin-sealed type semiconductor device not having bus-bar leads, predetermined spacings are provided not by interposing the insulating film between the major face of the semiconductor chip and the inner lead portions, and only the leading end portions of the inner lead portions are fixed to the major face of the semiconductor chip directly with adhesive. However, the uppermost layer of the major face of the semiconductor chip is an insulating film capable of ensuring the insulation between the semiconductor chip and the leads. As a result, the steps of manufacture are the cost can be reduced correspondingly to the elimination of the bus-bar leads and the insulating film. 

We claim:
 1. A semiconductor device comprising: a semiconductor chip including an integrated circuit and external terminals formed in a major surface thereof; a first lead and a second lead, each having an inner lead and an outer lead which is formed integrally with said inner lead, said inner lead of each of said first and second leads having a first portion which extends on said major surface of said semiconductor chip and a second portion which is outside of said semiconductor chip; bonding wires electrically connecting said inner leads of said first and second leads with the corresponding external terminals of said external terminals, respectively; and a resin member sealing said semiconductor chip, said inner leads of said first and second leads and said bonding wires, wherein a thickness of said first portion of each of said first and second leads is thinner than a thickness of said second portion of each of said first and second leads in a thickness direction of said semiconductor chip, wherein said first portion of said first lead is spaced from said major surface of said semiconductor chip in said thickness direction of said semiconductor chip, and wherein said first portion of said second lead is bonded to said major surface of said semiconductor chip by an adhesive layer formed between said first portion of said second lead and said major surface of said semiconductor chip.
 2. A semiconductor device according to claim 1, wherein each of said first and second leads has an upper surface and a lower surface which is opposite to said upper surface and is closer than said upper surface with respect to said major surface of said semiconductor chip, and wherein each of said first and second leads has a stepped portion which is formed at said lower surface.
 3. A semiconductor device according to claim 1, wherein a degree of said stepped portion corresponds to a differential of thickness between said first and second portions of said inner lead of each of said first and second leads.
 4. A semiconductor device according to claim 3 wherein said lower surface positioned at said second portion of said inner lead of each of said first and second leads is disposed at a lower level than said major surface of said semiconductor chip in said thickness direction of said semiconductor chip.
 5. A semiconductor device according to claim 1, wherein said adhesive layer includes a thermoplastic polyimide adhesive.
 6. A semiconductor device according to claim 1, wherein an end of said first portion of said inner lead of said second lead is offset toward said major surface of said semiconductor chip, and wherein said adhesive layer is formed between said end of said first portion of said inner lead of said second lead and said major surface of said semiconductor chip.
 7. A semiconductor device according to claim 6, wherein said adhesive layer is formed partially between said major surface of said semiconductor chip and said first portion of said inner lead of said second lead, and wherein one end of said bonding wire is contacted with said end of said first portion of said inner lead of said second lead at which said adhesive layer is formed.
 8. A semiconductor device according to claim 1, wherein said first lead includes a signal lead and said second lead includes a fixed potential lead.
 9. A semiconductor device according to claim 1, wherein said adhesive layer is an adhesive which does not include a base insulating tape. 